Boost.Factory Example

#include <map>
#include <iostream>
#include <string>

#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/functional/factory.hpp>

using namespace std;

// http://www.boost.org/doc/libs/1_53_0/libs/functional/factory/doc/html/index.html#boost_functional_factory.reference.factory

struct Base
{
    string name;
    Base(const string &name)
        : name(name)
    { }
    virtual ~Base()
    {
        cout << "Good bye, " << name << "\n";
    }
    virtual void stuff()
    {
        cout << "Name: " << name << "\n";
    }
};

typedef boost::shared_ptr<Base> BasePtr;


struct ChildA : public Base
{
    ChildA(const string &name)
        : Base(name)
    { }
    void stuff()
    {
        Base::stuff();
        cout << "Child A\n";
    }
};

typedef boost::shared_ptr<ChildA> ChildAPtr;


struct ChildB : public Base
{
    int apples;
    ChildB(const string &name, int apples = 12)
        : Base(name), apples(apples)
    { }
    void stuff()
    {
        Base::stuff();
        cout << "Child B has " << apples << " apples\n";
    }
};

typedef boost::shared_ptr<ChildB> ChildBPtr;

namespace boost {
    // Add in a simple wrapper for a factor creating shared pointers
        template<typename T>
    struct shared_factory : public factory<shared_ptr<T> >
    { };
}

int main(int argc, char **argv)
{
    typedef boost::function<BasePtr (const string &name)> Factory;
    typedef map<string, Factory> FactoryMap;
    FactoryMap factoryMap;
    factoryMap["a"] = boost::shared_factory<ChildA>();
    factoryMap["b"] = boost::shared_factory<ChildB>();
    // http://stackoverflow.com/questions/1335301/using-boostbind-with-a-constructor
    factoryMap["b_overload"] = boost::bind(boost::shared_factory<ChildB>(), _1, 6);

    BasePtr test = factoryMap["a"]("Test1");
    test->stuff();

    cout << "\nNew object in same pointer (dtor)\n\n";
    test = factoryMap["b"]("Test2");
    test->stuff();

    cout << "\nOverloading bound apples to 6 (default was 12)\n\n";
    test = factoryMap["b_overload"]("Test3");
    test->stuff();

    return 0;
}

/*
Name: Test1
Child A

New object in same pointer (dtor)

Good bye, Test1
Name: Test2
Child B has 12 apples

Overloading bound apples to 6 (default was 12)

Good bye, Test2
Name: Test3
Child B has 6 apples
Good bye, Test3
*/